Report WebGL errors

sample/js/error.js

@@ -0,0 +1,17 @@
+const canvas = document.getElementById("renderCanvas");
+const gl = canvas.getContext("webgl");
+
+function loop() {
+    gl.clearColor(0.3, 0.3, 0.3, 1.0);  // Clear to black, fully opaque
+    gl.clearDepth(1.0);                 // Clear everything
+    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
+
+    console.log(gl.getError(), "before")
+    gl.clear(0xFFFF)
+    console.log(gl.getError(), "after")
+
+    window.requestAnimationFrame(function() {
+        loop();
+  });
+}
+loop();

src/backend/commands/baseCommand.ts

@@ -17,7 +17,7 @@ export abstract class BaseCommand {
         // Includes uniform functions special cases to prevent lots of inheritence.
         const text = (functionInformation.name.indexOf("uniform") === 0) ?
             this.stringifyUniform(functionInformation.arguments) :
-            this.stringify(functionInformation.arguments, functionInformation.result);
+            this.stringify(functionInformation.arguments, functionInformation.result, functionInformation.errors);
 
         const commandCapture = {
             id: commandCaptureId,
@@ -81,14 +81,17 @@ export abstract class BaseCommand {
         // Nothing by default.
     }
 
-    protected stringify(args: IArguments, result: any): string {
+    protected stringify(args: IArguments, result: any, errors: any[]): string {
         let stringified = this.spiedCommandName;
         if (args && args.length > 0) {
             stringified += ": " + this.stringifyArgs(args).join(", ");
         }
         if (result !== undefined && result !== null) {
             stringified += " -> " + this.stringifyResult(result);
         }
+        if (errors.length > 0) {
+            stringified += " ~> " + errors.map(error => this.stringifyValue(error)).join(", ");
+        }
         return stringified;
     }
 

src/backend/spies/commandSpy.ts

@@ -113,13 +113,41 @@ export class CommandSpy {
         // tslint:disable-next-line:only-arrow-functions
         return function () {
             const before = Time.now;
-            const result = OriginFunctionHelper.executeOriginFunction(self.spiedCommandRunningContext, self.spiedCommandName, arguments);
+            let result = OriginFunctionHelper.executeOriginFunction(self.spiedCommandRunningContext, self.spiedCommandName, arguments);
             const after = Time.now;
 
-            const functionInformation = {
+            // Initialize error logging
+            const gl = self.spiedCommandRunningContext;
+            if (!gl.currentErrors) {
+                gl.currentErrors = [];
+            }
+
+            const newErrors = []
+            if (self.spiedCommandName === 'getError') {
+                // Inject one of the collected errors
+                result = gl.currentErrors.shift() ?? gl.NO_ERROR;
+            } else {
+                // Record new errors
+                while (true) {
+                    const errorResult = OriginFunctionHelper.executeOriginFunction(gl, "getError", undefined);
+                    if (errorResult === gl.NO_ERROR) {
+                        break;
+                    }
+                    newErrors.push(errorResult);
+                }
+                // Move new errors to the accumulated list
+                newErrors.forEach(newError => {
+                    if (!gl.currentErrors.includes(newError)) {
+                        gl.currentErrors.push(newError);
+                    }
+                });
+            }
+
+            const functionInformation: IFunctionInformation = {
                 name: self.spiedCommandName,
                 arguments,
                 result,
+                errors: newErrors,
                 startTime: before,
                 endTime: after,
             };

src/backend/types/functionInformation.ts

@@ -6,6 +6,7 @@ export interface IFunctionInformation {
     readonly name: string;
     readonly arguments: IArguments;
     readonly result: any;
+    readonly errors: any[];
     readonly startTime: number;
     readonly endTime: number;
 }